A pipeline constructed of pipe sections welded together requires inspection to insure that the weld is properly made. While it is usually simple to inspect the weld outside the pipeline, it becomes more difficult to inspect the portion of the weld inside the pipeline. Visual inspection of the weld can detect weld gaps or improper welds, permitting the weld to be redone before the pipeline is pressurized.
In large pipes, it is possible for a man to actually crawl into the pipe for inspection. However, many pipelines are too small for this, and even for larger pipelines, actual inspection is a time consuming and expensive endeavor. A need therefore exists for a more efficient and cost-effective mechanism for visual inspection of welds within a pipeline.